The twitter thread (nitter is a twitter mirror) uses the same data Zenz uses. But also, you should consider reading the rest of it. Zenz was not saying he made a mistake or that he should have paid more attention, he was saying that about his critics. He then answered the criticisms with more statistical sleight of hand that he doubled down on.

SUMMARY OF THE STATISTICAL SLEIGHT OF HAND OUTLINED IN THE LINK.

The statistic Zenz gives — that “80% of net IUD insertions in China were in XJ” — is extremely misleading because the percent is not out of 100. Using his math, many provinces have percentages below 0, because we are comparing net values. When you add up net values for all of China, negatives and positives cancel, giving a small denominator.

(Xinjiang insertions - removals) / (China insertions - removals) = a nonsense percentage, potentially negative, potentially dividing by zero

If you add up Xinjiang, Henan and Hebei you get 210%

So it's not just a simple mistaken wording, the statistic itself was fundamentally nonsense from the start.

To drive the point home: In 2014, per the twitter thread, Xinjiang net insertions were roughly the same as in 2018, but China net insertions were much higher, so Xinjiang’s percent was only 2.5% rather than 80%, even though there was no significant change in Xinjiang.

Which brings me to the next point: There is a time element to the story. Less-developed provinces, where access to reproductive health services is still expanding, will have more net insertions, because there are fewer older people removing old IUDs. But over the years, insertions and removals will balance out, and can even dip negative in aging populations that have had IUD access for a long enough time. An underdeveloped province that is still expanding reproductive health access will have more net insertions than other provinces. It is expected that provinces will have high net insertions early in that timeline.

What's missing is the actual number of IUDs in Xinjiang, which would be illuminating.